1. Field of the Invention
This invention relates to an easy open type can which can be opened by breaking a score line.
2. Description of Background Art
A can has been hithertofore known, as shown in FIG. 7, wherein an open portion of a can barrel a is hermetically closed by mounting a metallic can closure g on an open end portion b of the can barrel a. A score line e is provided along the whole circumference of an upper edge of a peripheral wall portion d thereof extending downwards from the whole circumferential edge of a top panel portion c. A tab f for breaking the score line e is provided on a lower edge of the peripheral wall portion d so as to be connected thereto.
However, this construction requires the score line formed in the metallic can closure g for hermetically closing the open portion h of the can barrel a to be made therein so as to have a predetermined constant depth for every metallic can closure. Accordingly, quality control is very difficult in making the cans. Additionally, for preventing the can closure from being broken at the socre line by vibrations or a shock given during transportation thereof, it is necessary to use a can closure which is comparatively large in thickness. Increasing the thickness increases the weight of the can, and increases the cost in producing the can. Further, a difficulty arises in incineration of the can after use.
In addition, an easy open type can is known wherein an open portion h' of a can barrel thereof is hermetically closed by a plastic closure with a score line made in a center region of a top panel portion thereof. A tab for breaking the score line is provided on an upper surface of the top panel portion. This can construction is disclosed in Japanese Patent Application Kokai No. Sho 59-199462. In more detail, the above type of easy open type can is shown in FIGS. 8 and 9. Namely, a can closure o' for hermetically closing an open end portion b' of a can barrel a' is made of a plastic panel composed of a heat sealable resin inner layer member d' and a gas impermeable resin layer e'. A score line f' for defining a region of the plastic panel that is to be opened toward the center of the plastic panel is constructed in the can closure c' so as to reach only the layer e' of the plastic panel. A tab g' for breaking open the can closure c' at this region is provided in the region of the plastic panel so as to be combined therewith in such a manner as shown in FIGS. 8 and 9.
However, with this construction, if the can closure c' is pushed from above or a force is applied with an internal pressure which is increased by the carbonated type of contents of the can, or the can is subjected to a shock during transportation of the can, may result in that the plastic panel constituting the can closure c' may be deformed. In addition, the closure may be torn open as a result of distortion made at the thin portion containing the score line f'. Accordingly, it is required to increase the thickness of the inner layer member d' of the plastic panel.